TEHRAN (Tasnim) - Secret US documents show that top officials in Pakistan's government have for years known and secretly endorsed CIA drone strikes that have killed hundreds of people in that country.

The Washington Post said it had obtained CIA documents and Pakistani diplomatic memos which indicated officials were routinely given classified briefings, BBC reported. Pakistan has responded by repeating its opposition to drone strikes.

Pakistan's PM Nawaz Sharif has publicly urged US President Obama to halt such attacks.

"I also brought up the issue of drones in our meeting, emphasising the need for an end to such strikes," Mr Sharif said after the two met on Wednesday.

The attacks by unmanned US aircraft have been a critical source of tension in the relationship between the countries and came up amid wide-ranging talks between the leaders in Washington.

They are also deeply unpopular with the Pakistani public, and Pakistan has consistently stated that they violate its sovereignty.

The Pakistani government has responded to the report by repeating its opposition to US drone strikes. "Whatever understandings there may or may not have been in the past, the present government has been very clear regarding its policy on the issue," the Pakistani foreign ministry said in a statement.

"We regard such strikes as violation of our sovereignty as well as international law," it said, adding that they were also counterproductive.

The documents obtained by the newspaper focus on at least 65 drone strikes in Pakistan over the last few years and were labeled as "talking points" for regular CIA briefings.

In the Pakistani tribal areas, details of casualties in drone strikes have invariably been provided to the media by intelligence agents posted there. They often display considerable knowledge about the targeted buildings, and give precise numbers and identities of some of the people killed.

In the early days of the drone program, when such strikes were practically unheard of, these agents actively prevented local journalists from publicizing evidence about the attacks.

Although they are marked "top secret" they are cleared for release to Pakistan, the paper reports.

The Washington Post says the documents provide a detailed timeline of the CIA drone program "tracing its evolution from a campaign aimed at a relatively short list of senior al-Qaeda operatives into a broader aerial assault against militant groups with no connection to the 11 September 2001 attacks".

In 2010 the controversial whistle blowing site Wikileaks released numerous documents relating to Pakistan which showed the Pakistani military and other arms of the government had "quietly acquiesced" with drone strikes even though they had publicly condemned them.

In August 2008 then Prime Minister Yousuf Raza Gilani is reported to have said: "I don't care if they do it as long as they get the right people. We'll protest in the National Assembly and then ignore it."

But this latest cache includes documents which appear to refer to a direct Pakistani role in the selection of targets, with the newspaper referring to one 2010 entry describing hitting a location "at the request of your government".

There is also a reference to a "network of locations associated with a joint CIA-ISI targeting effort".

Earlier this week, Amnesty International released a report which said that CIA drone attacks in Pakistan were responsible for unlawful killings, some of which could amount to war crimes. The rights group named several victims who, it says, "posed no threat to life".

Amnesty said it reviewed nine of 45 recent drone strikes in the volatile tribal region of North Waziristan where many strikes have hit, and found a number of victims had been unarmed.

The US has defended its drone strikes in Pakistan and elsewhere. On Tuesday the White House said it took "extraordinary care" to ensure they complied with international law and that they were a "course of action least likely to result in the loss of innocent life".

A recent UN report also found that US drone strikes had killed at least 400 civilians in Pakistan, far more than the US has ever acknowledged. Estimates by other groups such as the Bureau of Investigative Journalism calculate that between 407 and 926 civilians have been killed in Pakistan.